The invention relates to a tool-clamping device for clamping a forming tool, such as a bending punch, on a compression beam in a press such as an edging press, with a tool adapter attached to the compression beam to releasably hold the forming tool.
In order to releasably hold forming tools, such as bending dies or bending punches for example, on a compression beam in a press, in particular in an edging press, a known approach is to provide tool adapters extending in the longitudinal direction of the compression beam and fixed thereto in a stationary arrangement, so that they form a groove-shaped holder for the tools. The tools are held in position in the holder by a clamping device. The tool adapter and the tools are designed as matching modules and a compression beam is fitted with the tool adapter by contact friction along a portion of the length of the compression beam.
The tool adapter of this known design is attached to a side face of the compression beam and, in order to transmit the compression force, has a compression piece which co-operates with the side face of the compression beam and is moved into abutment therewith. The disadvantage of this design is that the bending deformation of the compression beam and the tool adapters conforming to the bending line during a compression process cause an undefinable relative displacement in the direction of the longitudinal extension of the compression beam between the latter and the tool adapters as a result of the different radius of the neutral zone to the curvature mid-point. Under extreme circumstances, this can cause the tool adapter to migrate from a pre-defined position on the compression beam within a clearance dependent on tolerances. This relative shifting, which also occurs between the bottom and top tool, results in incorrectly processed workpieces and hence in more demanding control requirements and increased costs.
Accordingly, the objective of the invention is to propose a tool-clamping device designed so that the tool adapters are returned to the original position once the compression process producing the bend is terminated and the tool adapter changes position relative to the compression beam.
This objective is achieved by providing a tool-clamping device for affixing a forming tool on a compression beam in a press, comprising a tool adapter structured and arranged to releasably hold the forming tool, the tool adapter having a receiving region for receiving the forming tool and a connecting region structured and arranged to engage the compression beam, the tool adapter further comprising at least one resiliently elastic return means disposed between the forming tool and the compression beam, the return means being elastically deformed by relative displacement between the forming tool and the compression beam in a longitudinal direction of the beam as a result of deformation of the beam caused by force exerted on the beam during a compression process, the return means restoring the tool adapter to an initial position thereof when the force on the beam is removed.
In some advantageous embodiments, the return means is created by material splits formed in the tool adapter so as to form resilient connecting webs between the receiving region and the connecting region of the adapter. As a result, the receiving region of the tool adapter is able to effect compensating motions in the longitudinal direction of the compression beam relative to the connecting region in which the tool adapter is connected to the compression beam in a friction lock arrangement, and the friction-lock connection is not placed under strain from lateral forces as a result, so that the receiving region is automatically returned to the initial position on completion of the compression stroke.
Other advantageous embodiments include sliding or rolling elements between the opposing surfaces of the tool adapter and the compression beam such that the friction between the adapter and the compression beam is reduced and the resultant different longitudinal expansions during the bending action are compensated, enabling the tool adapter to be returned to the initial position.
In one embodiment the return means comprise resiliently elastic fixing elements such as screws that affix the tool adapter to the compression beam. The fixing elements provide the return forces needed to cause the tool adapter to be returned to its initial position.
In another possible embodiment the requisite return forces are achieved using structurally simple machine elements that do not incur any significant degree of effort in terms of assembly during manufacture of the system.
Finally, another embodiment is of advantage because it enables the lateral deflection and rebound behavior in the tool adapter to be selectively fixed between the receiving and the connecting region.